<?php
/* 
 * Create interactive index:
 * In a Textflow define some terms to be indexed and create a sorted index from
 * the indexed terms
 *
 * For indicating an indexed term in a Textflow use the inline options 
 * "matchbox" and "matchbox end" to create a matchbox at the position to which
 * the index entry will refer to. The matchbox name will be similar to the 
 * indexed term. Place the Textflow. Then, create the index by collecting all
 * matchboxes. Each index entry will consist of the matchbox name (indexed term)
 * and the respective page number. Provide the page number with a link
 * annotation to jump to the respective page. Matchboxes are used here a 
 * second time to indicate the active link area on the page number.
 * 
 * Required software: PDFlib/PDFlib+PDI/PPS 10
 * Required data: none
 */
$searchpath = dirname(__FILE__,3)."/input";
$outfile = "";
$title = "Create Interactive Index";

$llx = 20; $lly = 20; $urx = 200; $ury = 200;
$pagewidth = 250; $pageheight = 230;

$tf = 0; $idx = 0;
 

/* Option list to indicate the start of a matchbox */
$startopts = "";

/* Option list to indicate the end of a matchbox */
$endopts = "matchbox=end";

/* Standard option list for adding a Textflow.
 * "avoidemptybegin" deletes empty lines at the beginning of a fitbox.
 * "charref" enables the substitution of numeric and character entity
 * or glyph name references, e.g. of the character reference "&shy;"
 * for a soft hyphen.
 */
$stdopts = "fontname=NotoSerif-Regular fontsize=12 leading=120% charref avoidemptybegin ";
   
$ntexts = 10;
  
/* The text array contains pairs of strings. Each first string will be used
 * as indexed term, i.e. the text of an index marker.
 */
$texts = array(
    "Long Distance Glider",
    "\nWith this paper rocket you can send all your messages even when " .
    "sitting in a hall or in the cinema pretty near the back.\n\n",
    
    "Giant Wing",
    "\nAn unbelievable sailplane! It is amazingly robust and can even " .
    "do aerobatics. But it best suited to gliding.\n\n",
    
    "Cone Head Rocket",
    "\nThis paper arrow can be thrown with big swing. We launched it " .
    "from the roof of a hotel. It stayed in the air a long time and " .
    "covered a considerable distance.\n\n",
    
    "Super Dart",
    "\nThe super dart can fly giant loops with a radius of 4 or 5 " .
    "metres and cover very long distances. Its heavy cone point is " .
    "slightly bowed upwards to get the lift required for loops.\n\n",
    
    "German Bi-Plane",
    "\nBrand-new and ready for take-off. If you have lessons in the " .
    "history of aviation you can show your interest by letting it " .
    "land on your teacher's desk.\n\n",
);

/* Index entry containing a name and a page number. For sorting the index
 * entries a compare method is provided.
 */

try {
    $p = new pdflib();

    $p->set_option("searchpath={" . $searchpath . "}");

    /* This means we must check return values of load_font() etc. */
    $p->set_option("errorpolicy=return");
 
    /* Start the output document */
    if ($p->begin_document($outfile, "") == 0)
        throw new Exception("Error: " . $p->get_errmsg());

    $p->set_info("Creator", "PDFlib Cookbook");
    $p->set_info("Title", $title );
    
    
    /* ----------------------------------------------------------------
     * Add the text Textflow and define a matchbox on each indexed term
     * ----------------------------------------------------------------
     */
    
    /* Supply the standard options to the Textflow. This has to be done
     * only once. Further calls of add_textflow() for this Textflow will use
     * these settings by default.
     */
    $tf = $p->add_textflow(0, "", $stdopts);
    if ($tf == 0)
        throw new Exception("Error: " . $p->get_errmsg());
    
    /* Loop over all texts. Add each text and define a matchbox on each
     * indexed term. The matchbox name is set to the indexed term.
     */
    for ($i = 0; $i < $ntexts; $i+=2) {
        /* Add text and start a matchbox indicating an indexed term.
         * Colorize the matchbox rectangle (only for illustration purposes)
         */
        $startopts = "matchbox={name={" . $texts[$i] . "} " .
            "fillcolor={rgb 0 0.95 0.95}}";
    
        $tf = $p->add_textflow($tf, $texts[$i], $startopts);
        if ($tf == 0)
            throw new Exception("Error: " . $p->get_errmsg());
        
        /* Add text and finish the matchbox */
        $tf = $p->add_textflow($tf, $texts[$i+1], $endopts);
        if ($tf == 0)
            throw new Exception("Error: " . $p->get_errmsg());
    }
    
    
    /* --------------------------------------------------------------------
     * Place the text and retrieve all matchboxes (indexed terms) to create
     * the index entries from
     * --------------------------------------------------------------------
     */
        
    /* Initialize the current page number to be output in the index */
    $pageno = 0;
    
    /* Initialize the number of index entries */
    $entryno = 0;
    
    /* Loop until all of the text is placed; create new pages as long as
     * more text needs to be placed.
     */
    do
    {
        $p->begin_page_ext($pagewidth, $pageheight, "");
        $pageno++;

        /* Place the text */
        $result = $p->fit_textflow($tf, $llx, $lly, $urx, $ury, "");
        
        /* Place a page number at the lower right corner of the page */
        $p->fit_textline($pageno, $pagewidth - 20, 10, 
            "fontname=NotoSerif-Regular fontsize=12 fillcolor={rgb 0 0.95 0.95}");
        
        /* Create the index by creating an index entry from each matchbox on
         * the page. Create an index entry by retrieving the matchbox name
         * as well as the current page number.
         * 
         * (In our solution multiple index entries may refer to the same
         * indexed term. An indexer for general use would combine entries
         * for the same term into a single index entry with multiple
         * page numbers. Implement this by creating a chain of multiple
         * matchboxes for each indexed term.)
         */
        
        /* Query the number of matchboxes on the page; the "num" parameter
         * is set to 0 and will be ignored
         */
        $mcount = $p->info_matchbox("*", 0, "count");
        
        for ($i = 1; $i <= $mcount; $i++)
        {
            /* Get the matchbox name */
            $minfo = $p->info_matchbox("*", $i, "name");
        
            $mname = $p->get_string($minfo, "");
            
            /* Retrieve the name of the matchbox to be used as the indexed 
             * term and the page number to be used as the page number in the
             * index entry
             */
            $newEntry[] = array("name" => $mname, "page" => $pageno);
                  
            $entryno++;
        }
         
        $p->end_page_ext("");

        /* "_boxfull" means we must continue because there is more text;
         * "_nextpage" is interpreted as "start new column"
         */
    } while ($result == "_boxfull" || $result == "_nextpage");

    /* Check for errors */
    if (!$result == "_stop")
    {
        /* "_boxempty" happens if the box is very small and doesn't
         * hold any text at all.
         */
        if ($result ==  "_boxempty")
            throw new Exception ("Error: Textflow box too small");
        else
        {
            /* Any other return value is a user exit caused by
             * the "return" option; this requires dedicated code to
             * deal with.
             */
            throw new Exception ("User return '" . $result .
                "' found in Textflow");
        }
    }

    $p->delete_textflow($tf);
    

    /* -------------------------------------------------------------
     * Sort the list of index entries. Convert it to an array first.
     * -------------------------------------------------------------
     */

    $sortedIndex = $newEntry;
    usort($sortedIndex, "cmp");
    
    
    /* ---------------------------------------------------------------------
     * Construct the contents of the index page(s) based on the collected
     * pairs containing the indexed term plus the corresponding page number
     * ---------------------------------------------------------------------
     */ 
    /* Supply the standard options to the index Textflow. This has to be 
     * done only once for each Textflow. Further calls of add_textflow() for
     * this Textflow will use these settings by default.
     */
    $idx = $p->add_textflow(0, "", $stdopts);
    if ($idx == 0)
        throw new Exception("Error: " . $p->get_errmsg());
   
    /* Add the heading "Index" to the index Textflow */
    $idx = $p->add_textflow($idx, "Index\n\n", "");
    if ($idx == 0)
        throw new Exception("Error: " . $p->get_errmsg());
    
    /* Add the collected and sorted index entries to the index Textflow */
    for ($i = 0; $i < count($sortedIndex); $i++) {
        /* Add the indexed term of the index entry */
        $idx = $p->add_textflow($idx, $sortedIndex[$i]["name"] . "  ", 
            "fillcolor={gray 0}");
        if ($idx == 0)
            throw new Exception("Error: " . $p->get_errmsg());
        
        /* Add the page number of the index entry. In addition, define a
         * matchbox with a sequence number as the name. This matchbox will 
         * be used later to define a link annotation on it to jump to the 
         * respective page. 
         */
        $idx = $p->add_textflow($idx, $sortedIndex[$i]["page"], 
            "fillcolor={rgb 0 0.95 0.95} matchbox={name=" . $i . "}");
        if ($idx == 0)
            throw new Exception("Error: " . $p->get_errmsg());
                  
        $idx = $p->add_textflow($idx, "\n", $endopts);
        if ($idx == 0)
            throw new Exception("Error: " . $p->get_errmsg());
    }
   
    
    /* ---------------------------------------------------------------------
     * Place the index Textflow with each entry consisting of a text, a page
     * number, and a link annotation on the page number
     * ---------------------------------------------------------------------
     */ 
       
    /* Initialize the current number of the index entry */
    $entryno = 0;
    
    /* Loop until all index entries are placed; create new pages as long as
     * more index entries need to be placed
     */
    do
    {
        $p->begin_page_ext($pagewidth, $pageheight, "");
        $pageno++;
        
        /* Fit the index Textflow */
        $result = $p->fit_textflow($idx, $llx, $lly, $urx, $ury, "");
        
        /* Place a page number */
        $p->fit_textline($pageno, $pagewidth - 20, 10, 
            "fontname=NotoSerif-Regular fontsize=12 fillcolor={rgb 0 0.95 0.95}");
        
        /* Collect the index entries by retrieving the number of matchboxes
         * on the current page
         */
        $mcount = $p->info_matchbox("*", 1, "count");
        
        for ($i = 1; $i <= $mcount; $i++)
        {
            /* Get the matchbox name which corresponds to the text of the
             * index entry
             */
            $minfo = $p->info_matchbox("*", $i, "name");
        
            $mname = $p->get_string($minfo, "");
            $action = $p->create_action("GoTo", "destination={page=" .
                ($sortedIndex[$entryno]["page"]) . "}");
            
            /* With the "GoTo" action, create a Link annotation on the 
             * matchbox defined above. 0 rectangle coordinates will be
             * replaced with matchbox coordinates.
             */
            $p->create_annotation(0, 0, 0, 0, "Link", 
                "action={activate " . $action . "} linewidth=0 " . 
                "usematchbox={" . $mname . "}");
            
            $entryno++;
        }
        $p->end_page_ext("");
        
    } while ($result == "_boxfull" || $result == "_nextpage");

    /* Check for errors */
    if (!$result == "_stop")
    {
        /* "_boxempty" happens if the box is very small and doesn't
         * hold any text at all.
         */
        if ($result ==  "_boxempty")
            throw new Exception ("Error: Textflow box too small");
        else
        {
            /* Any other return value is a user exit caused by
             * the "return" option; this requires dedicated code to
             * deal with.
             */
            throw new Exception ("User return '" . $result .
                "' found in Textflow");
        }
    }

    $p->delete_textflow($idx);

    $p->end_document("");

    $buf = $p->get_buffer();
    $len = strlen($buf);

    header("Content-type: application/pdf");
    header("Content-Length: $len");
    header("Content-Disposition: inline; filename=create_interactive_index.pdf");
    print $buf;

} catch (PDFlibException $e) {
    echo("PDFlib exception occurred:\n".
        "[" . $e->get_errnum() . "] " . $e->get_apiname() .
        ": " . $e->get_errmsg() . "\n");
    exit(1);
} catch (Throwable $e) {
    echo("PHP exception occurred: " . $e->getMessage() . "\n");
    exit(1);
}

$p = 0;

function cmp($a, $b) {
    return strcmp($a["name"], $b["name"]);
}
?>